Organ of Sight, 151 



8. The Lig amentum pectinatum 



in Man consists of slight festoon-like processes of the fihres of the 

 Iris, lying in a transparent elastic fibrous tissue, continuous with 

 the posterior elastic layer of the Cornea : 



in the eyes of the Sheep and Ox it is a more developed structure 

 than in the Human eye, and in them the festooned processes are 

 prominent, giving a milled appearance like that of the edge of a 

 coin. 



Racemiform bodies projecting from the Uvea are found in the 

 Solidungula and Euminantia generally. 



9. The Tapetum 



in colour is 



usually green in Perissodactyla* (except in Horse, in which it 

 is light Hue) ; in most Artiodactyla (being, however, chocolate in the 

 Hog), and in Proboscidia : but is silvery white in the Cete, and most 

 Sectoralia (except in the Felidae, in which it is amber, and the Canidse, 

 in which it is white, edged with blue) : 



in structure 



it consists of tetidinous fihres in Euminantia and Proboscidia : and 

 of cells filled with granular matter in Sectorialia. 



in form 



it is broadly crescentic in Felidce (Sectorialia). 



10. The Retinal spot. 



Quadrumana. This spot, situated in or very near the axis of 

 vision, exists in the Catarrhina as in Man : but has been found in 

 no Lemurine (in which a minute fold or crease occupies its place). 



11. HhQ Eyelids 



are single and circular 

 in Monotremata. 



In Cete the eyelids are represented by a continuous circular fold 

 of the skin, leaving a round opening in front of the eye, with a 

 narrow margin unprovided with eyelashes : this is also the case 



in Seals (Sectorialia), where however an external groove indicates 

 the division of the horizontal eyelids. 



The upper Eyelid is provided with Cilia 



in all Euminantia ; they are especially long in Giraffe. 



* It is absent in Ehinoceros. 



